Enrichment and characterization of a noble gas fullerene: ArC⁶⁰

ArC₆₀ synthesized by heating primarily C₆₀ (with trace amounts of C₇₀ under a high pressure of argon gas,was purified by high-performance liquid chromatography (HPLC) and examined by Fourier transform mass spectrometry (FTMS). The sample, which consisted of 0.1% ArC₆₀, was dissolved in toluene and separated with HPLC using a COSMOSIL 5PYE column as the stationary phase and toluene as the eluent (UV detection). ArC₆₀ was enriched by a factor of about 400 relative to the starting material. ArC₆₀ was also examined by X-ray photoelectron spectroscopy (XPS) but was found to be sensitive to radiation damage and subsequent depletion. Low-energy collisional dissociation of Ar$+$/ C₆₀⁺ in the FTMS yields primarily C₅₈⁺, generated by loss of the argon atom and C₂. The ionization potential of Ar$+$/C₆₀ was bracketed by charge-exchange reactions and was found to be between 7.53 and 7.8 eV, which is indistinguishable from that of C₆₀ (7.65 eV).